Steering arrangement for a ship propelled by waterjet

ABSTRACT

The present invention relates to a steering arrangement for ships propelled by water jet, comprising a steering device ( 6 ) that is pivotal about an essentially vertical shaft ( 5 ) having a first center line (C 1 ), at least one hydraulic cylinder ( 2; 3 ) for turning said steering device ( 6 ), which hydraulic cylinder is directly or indirectly articulately connected to the ship&#39;s body at one of its ends ( 2 B;  3 B), a turning device ( 4 ) connected to said shaft ( 5 ), for attachment to a second end ( 2 A;  3 A) of said hydraulic cylinder at a distance from said shaft ( 5 ), a reversing device ( 7 ) arranged in connection with said steering device ( 6 ) about an essentially horizontal shaft ( 12 ), an additional hydraulic cylinder ( 9 ) arranged to act on the reversing device ( 7 ), the additional hydraulic cylinder ( 9 ) following the movement of the steering device ( 6 ), characterized in that all the hydraulic cylinders ( 2,3,9 ) are arranged within a sheltered space ( 1 ) located above the extension of said vertical shaft ( 5 ), which space ( 1 ) is accessible for maintenance from the inside of the ship, and in that the arranging of said hydraulic cylinder ( 9 ) at the turning device ( 4 ) in relation to the steering device ( 6 ) is arranged such that the relative position of the reversing device ( 7 ) is uninfluenced by the relative position of the steering device ( 6 ).

TECHNICAL FIELD

The present invention relates to a steering arrangement for shipspropelled by water jet, comprising a steering device that is pivotalabout an essentially vertical shaft having a first centre line, at leastone hydraulic cylinder for turning said steering device, which hydrauliccylinder is directly or indirectly articulately connected to the ship'sbody at one of its ends, a turning device connected to said shaft, forattachment to a second end of said hydraulic cylinder at a distance fromsaid shaft, a reversing device arranged in connection with said steeringdevice about an essentially horizontal shaft, an additional hydrauliccylinder arranged to act on the reversing device, the additionalhydraulic cylinder following the movement of the steering device.

STATE OF THE ART AND PROBLEM

Large water jet units have lately become more and more popular fordriving bigger ships. Steering a ship with water jet is achievedaccording to a well-known principle by means of a box-shaped, pivotingsteering device controlled by powerful hydraulic cylinder units, and areversing device controlled by its own hydraulic cylinder and suspendedin the steering device. However, the hydraulics is placed in the water,that is, outside the body. This involves a potential environmentalhazard since the conduits with hydraulic oil for the cylinders mightbreak and cause leakage of hydraulic oil into the water. It is a wishfrom some clients that this potential safety hazard is eliminated.

It is known to solve said problem by moving the hydraulic pistons insidethe craft's transom frame and instead control the steering device andthe reversing device suspended in the steering device by means of linkedmechanisms, which are described in “Speed at Sea” in the June-number2000. Because of the location of the reversing device these linkedmechanisms are very long and cumbrous. Since movements are desired inboth the vertical and the horizontal direction this solution also leadsto several hinges, which may cause problems concerning both structuralstrength and accuracy of steering. A major disadvantage is that therelative position of the reversing device is influenced at steering,which means that complicated steering electronics are required tocompensate for this influence.

An alternative solution to this problem is disclosed in U.S. Pat. No.3,422,788, where it is chosen not to make the whole steering devicepivoted but only a rudder-like element placed inside a kind of steeringdevice, which is fixed. The reversing device is, in its part, suspendedin the fixed steering device. Thus, the problem of the reversingdevice's influence is solved since the hydraulic piston that acts on thereversing device does not have to participate in any lateral movements.However, this solution involves many other considerable disadvantages,above all, an essentially deteriorated efficiency. Hence, it is not anacceptable solution.

Also through U.S. Pat. No. 3,807,346 a water jet is previously knownwhere the steering- and reversing devices are controlled by hydraulicsplaced in a sheltered position. However, this solution shows that thereversing device moves laterally, not vertically, which is theconventional and desirable solution. Hence, this alternativeconstruction is not desirable.

BRIEF DESCRIPTION OF THE INVENTION

It is an object of the present invention to find an optimal solution tothe above-described complex of problems. This is achieved by a steeringarrangement for ships propelled by water jet, comprising a steeringdevice that is pivotal about an essentially vertical shaft having afirst centre line, at least one hydraulic cylinder for turning saidsteering device, which hydraulic cylinder is directly or indirectlyarticulately connected to the ship's body at one of its ends, a turningdevice connected to said shaft, for attachment to a second end of saidhydraulic cylinder at a distance from said shaft, a reversing devicearranged in connection with said steering device about an essentiallyhorizontal shaft, an additional hydraulic cylinder arranged to act onthe reversing device, the additional hydraulic cylinder following themovement of the steering device, characterized in that all the hydrauliccylinders are arranged within a sheltered space located above theextension of said vertical shaft, which space is accessible formaintenance from the inside of the ship, and in that the arranging ofsaid hydraulic cylinder at the turning device in relation to thesteering device is arranged such that the relative position of thereversing device is uninfluenced by the relative position of thesteering device.

Thanks to this solution it is possible to achieve a sheltered, but fromthe inside of the ship accessible, inclusion of hydraulic hoses andconnections, and also a sheltered location of possible positionalmeasuring equipment for automatic control of the steering,simultaneously avoiding cumbrous linkage mechanisms that influence theposition of the reversing device.

According to further aspects of the invention:

-   -   the hydraulic cylinder controlling the reversing device is        articulately connected to a pivoting arm that in turn acts on a        link that is connected to a lever arm for the reversing device,    -   said centre line for said hydraulic cylinder comes close to,        preferably cuts, said first centre line,    -   said pivoting arm is arranged about a shaft the centre line of        which comes close to, preferably cuts, said first centre line,    -   said space has at least one wall that is part of the outer        boundaries of the ship, said wall preferably being arranged        above the water line,    -   positional measuring equipment for measuring the position of the        steering device and/or the reversing device is also arranged        inside said space,    -   the bottom part of said space is, at least partly, arranged        above, in close connection to the outlet part for the water jet        unit, and    -   two cylinders are used for turning said steering device, which        are articulately connected to the turning device with one of        their ends at both sides of said shaft,

DESCRIPTION OF DRAWINGS

The invention will be explained more in detail with reference to theattached drawings, wherein

FIG. 1 shows a preferred steering arrangement according to the inventionas a side view, partly in cross-section,

FIG. 2 shows the same view as FIG. 1 but with the reversing device inanother position,

FIG. 3 shows the steering arrangement according to FIG. 1 seen fromabove, partly in cross-section, and

FIG. 4 shows the same view as FIG. 3 but with the steering device inanother position.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2 there is shown in a side view two different positionsfor an arrangement according to the invention. The basic design of thesteering arrangement is made in a conventional way. Thus, a steeringarrangement known in itself is disclosed that comprises a steeringdevice 6 that is pivotal about a vertical shaft 5, which is fixed in thewater jet's outlet part 20 which in its turn is attached to the ship'stransom 30. Furthermore, this basic construction consists of a beamarrangement fixed at each side of the steering device and in which thereis arranged a hinge 12 for suspension of a lever arm 17 of a reversingdevice 7.

In FIG. 1 the reversing device is shown in its inactivated mode, thatis, a position for full speed ahead. At the same time, some parts of thesteering system are shown at a distance from the mounting position, forsake of lucidness.

In FIG. 2 the reversing device is shown in an activated mode, with thesteering system in the mounting position, where the jet stream thus isdiverted for the achievement of a reversing force.

The novel feature of this design is the arrangement of the hydrauliccylinders 2, 3, 9 and belonging mechanisms that act on steering device6, and reversing device 7 respectively. The cylinders 2, 3, 9 arearranged within a closed space 1 above the actual basic construction.The space is delimited astern by a plate 1A, that in the preferredembodiment extends essentially vertically in a plane abaft the verticalshaft 5. At the bottom, the space is delimited by a plate 1B that isessentially horizontal and attached to a transom stern 30, immediatelyabove the jet unit's attachment flange 11. The space 1 holds twocylinders 2, 3 for the turning mechanism and a cylinder 9 for thereversing device 7. In the turning mechanism there is included a turningdevice 4A, 4B that is fixed to and pivotal with the vertical shaft 5. Anupper half 4B of said turning device comprises a cylindrical part that,by bearings 37 (diagrammatically shown), is arranged to be pivotalinside a cylindrical bearing seat 38, which in its turn is fixed to abeam framework 25, 26, 27. At the upper half 4B, two axis journals 14A,14B are arranged (se FIG. 3), at which the front end 3A, 2A of thecorresponding hydraulic cylinder 2, 3 is articulately arranged forturning of the turning device 4 and thereby also of the steering device6.

Furthermore, a pivoting arm 15 is arranged at said upper half 4B of theturning device 4, which pivoting arm is pivotally arranged about anessentially horizontal axis 8, that is fixed in and follows the turningmovement of the upper half 4B. The lower part 15B of the pivoting arm isconnected to an inner end of a link 29, the outer end of which beingarticulately connected to the lever arm 17 for the reversing device 7.The other end 15A of the pivoting arm is articulately connected to thehydraulic cylinder 9, by an articulating shaft 13. In its other end 9B,this hydraulic cylinder 9 is articulately arranged at a shaft 9C. Theshaft 9C is arranged between two anchor bars 28A, 28B. The anchor bars28 are anchored to the upper half 4B of the turning device 4.Accordingly, the hydraulic cylinder 9 of the reversing device 7 isarranged above the turning device 4, so that is turns together with thatin its movement. The centre line C2 of the shaft 8 for the pivoting arm15 is arranged to cut the centre line C1 of the vertical shaft 5. Alsothe centre line C3 for the hydraulic cylinder 9 (see FIG. 4), isarranged to cut the centre line C1 of the vertical shaft 5. Thissuspension means that the relative position of the reversing device 7 inrelation to the pivoting arm 15, is uninfluenced by the relativeposition of the steering device 6. Accordingly, the reversing device 7will not change its relative position in relation to the pivoting arm 15even if the steering device 6 is turned to different positions, whichotherwise could be the case in accordance with prior art designs thatmake use of linkage mechanisms. The turning hydraulic cylinders 2, 3are, at their respective rear ends, articulately connected about an axisjournal 2B and 3B, respectively, that is arranged at the transversalbeam element 27, that in its turn is firmly anchored to the frameworkbeams 25, 26 that are fixed to the bearing seat 3B.

In the drawings, there is shown a possible embodiment for the sealing ofthe upper space 1, by the arrangement of a seal 39 that seals betweenthe pivoting arm 15 and the space inside the upper half 4B of theturning device 4. However, it should be pointed out that sealing maytake place in many different ways (e.g. by a sealing bellows beingarranged around the link 29 in the open space in the lower part 4A ofthe turning device), and that sealing in certain cases is not necessaryat all, if the space 1 is located high enough above the water line.

Inside said space 1, a manifold chamber (not shown) for hydraulic oil isarranged, from which chamber exits hydraulic hoses (not shown) forsupply and withdrawal of hydraulic oil to the hydraulic cylinders. Dueto this arrangement, both manifold chamber and hydraulic hoses will beplaced in a sheltered position within said space 1.

In FIG. 3, the steering arrangement according to the preferredembodiment is shown as seen from above. It shows the steering device 6is shown in a folded position, i.e. for driving straight ahead when thereversing device 7 is inactivated. The position in FIG. 3 is achieved bymeans of the hydraulic cylinders 2, 3 being positioned by each end 2A,3A of the piston rods, in a common plane which is parallel with the jetunit's attachment flange 11. From this position, by pushing out thepiston rod of the port hydraulic cylinder 3 and at the same time pullingin the piston rod of the starboard hydraulic cylinder 2, the turningdevice 4 is turned about the vertical shaft 5, so that the steeringdevice 6 is angled relative to the jet unit's attachment flange 11,which leads to a yaw.

Owing to the invention a sheltered location of the hydraulics isachieved without having to use cumbrous linkage mechanisms.

The invention is not limited to what has been described above but may bevaried within the scope of the claims. Thus, it is realized that it isnot necessary to have two hydraulic cylinders to act on the turningdevice but that in certain cases it is quite adequate only to have onehydraulic cylinder. However, two symmetrically placed hydrauliccylinders for the turning is preferable, not at least forreliability-/safety reasons. Furthermore, it is realized that theprinciple also may be used, by means of linkage mechanisms, to connectin parallel several adjacently arranged steering arrangements.

1. Steering arrangement for ships propelled by water jet, comprising: a)a steering device (6) that is pivotal in relation to the ship's bodyabout an essentially vertical center line (Cl); b) a turning device (4)fixedly connected to said steering device; c) at least one hydrauliccylinder (2; 3) for turning said steering device (6) via said turningdevice; d) a reversing device arranged in connection with said steeringdevice (6); and e) an additional hydraulic cylinder (9) arranged to acton the reversing device (7), wherein said at least one hydrauliccylinder is directly or indirectly articulately connected to the ships'body at one end of its ends (2B; 3B) and connected to said turningdevice at a second end (2A; 3A) at a distance from said center line,wherein all hydraulic cylinders (2, 3, 9) are arranged within asheltered space (1) located above the extension of said center line,which space (1) is accessible for maintenance from the inside of theship, wherein said reversing device is arranged about an essentiallyhorizontal shaft (12) on said steering device to follow the movement ofthe steering device (6), wherein said additional hydraulic cylinder (9)is arranged at the turning device (4) such that the relative position ofthe reversing device (7) is uninfluenced by the relative position of thesteering device (6), and wherein movement of said additional hydrauliccylinder produces a horizontal pivotal movement of said reversingdevice.
 2. Steering arrangement according to claim 1, characterised inthat the hydraulic cylinder (9) controlling the reversing device (7) isarticulately connected to a pivoting arm (15) that in its turn acts on alink (29) that is connected to a lever arm (17) for the reversing device(7).
 3. Steering arrangement according to claim 2, characterised in thatsaid centre line (C3) of said hydraulic cylinder (9) comes close to saidfirst center line (Cl).
 4. Steering arrangement according to claim 2,characterised in that said pivoting arm (15) is arranged about a shaft(8), the center line (C2) of which comes close to said first center line(C1).
 5. Steering arrangement according to claim 1, characterised inthat said space (1) has at least one wall (1A) that is part of the outerboundaries of the ship, said wall being arranged above the water line.6. Steering arrangement according to claim 1, characterised in thatpositional measuring equipment for measuring the position of thesteering device (6) and/or the reversing device (7) also is arrangedwithin said space.
 7. Steering arrangement according to claim 1,characterised in that said bottom part (1F) of said space (1) at leastfor some part is arranged above and in contact with, the outlet part(20) for the water jet unit.
 8. Steering arrangement according to claim1, characterised in that two cylinders (2, 3) articulately connected tosaid turning device (4) and with their first ends (2A; 3A) on each sideof said shaft (5), are used to turn the steering device (6).